Description
In this assignment, you will implement a collection class to manage a group of things of your choice.
Requirements
Part A: Implement your Thing class
In this assignment, you will implement a Thing class. Your Thing class to meet the following
requirements:
• You thing must have exactly 3 instance variables such that: o one instance variable must be
integer (i.e, int) and this variable will be used to find aggregate information (e.g., total or
max) about Things that are stored in a collection class as will be explained later.
o one instance variable must be String and this variable will be used as a
categorization attribute that will be used to divide your collection into groups. You
are going to use this attribute to count. For example, for a collection of cars, then the
cars can be categorized based on color or brand.
o The third instance variable can be either int or String type based on the semantics
of your Thing.
• All instance variables must be private.
• Implement getters and setters for all the instance variables of your Thing.
• Implement toString method that returns a String representation of your Thing class
where all the instance variables are in one line and separated by tabs.
• Implement the equals method for your Thing where two things are considered equal when
they have the same values in the three instance variables. Note that, the equality of String
attributes should be case insensitive. For example, “MATH”, “math” and “Math” match each
other. In order to compare strings in Java use the String’s equalsIgnoreCase method. For
example, the following code prints true:
String str1 = “Hello”;
String str2 = “hello”;
System.out.println(str1.equalsIgnoreCase(str2));
Part B: Implement a Collection class
• Implement a collection class of Things using an array.
1. You may NOT use any of the collection classes in Java library like ArrayList or
Vector or any other java collection class.
2. You must use simple java Arrays as we discussed in class during the BookCollection
demo.
• The name of your collection class should include the name of your Thing. For example, if your
Thing is called Country, then your collection class should be called
CountryCollection.
• Your collection class should include three instance variables as follows:
1. name: a String that represents a given name to a collection.
2. numItems: an int that represents the current number of items in the collection.
3. items: Thing[] which is an array that stores references to Thing objects.
• Implement a constructor for your collection class that takes two input parameters that
represent (1) the collection name, and the maximum number of elements that can be stored
in your collection.
• Implement the following methods in your collection class:
1. add: a method that takes one input parameter of type Thing. The method adds the
input thing to the collection.
2. add: overload the add method by implementing another add method that takes
three input parameters and the method uses these inputs to instantiate an object of
type Thing and adds it to the collection.
3. size: a method that returns the number of objects in the collection.
4. toString: a method that returns a String representation of the collection that
includes all elements that are stored in the collection. The output string must be nicely
formatted in a tabular format. For example, a list of students is to be displayed as
follows:
name grade major
—————————
John 20 CS
Eric 25 CIT
Hanna 30 Math Reem
27 CS
5. total: this method uses the int instance variable of the Thing class. Basically, the
method calculates and returns the sum of the int instance variable of all objects
stored in the collection. For example, in the student collection, this method finds the
sum of age of all students in the list.
6. greatest: this method returns the object with the maximum value in the int
attribute.
7. countCategory: this method takes one input parameter of type String that
represent one category of things in your collection (e.g., the input is ‘red’ in a
collection of Cars with ‘color’ attribute). The method counts and returns the number
of objects in the collection that falls in this category (e.g., the number of ‘red’ cars).
Note that String comparison must be case insensitive.
8. contains: this method takes one input parameter of type Thing. The method
searches for the input thing in the collection and returns true or false based on
whether the thing is found or no. Note, that you have to use the equals method to
compare the equality of classes.
9. countOccurances: this method takes one input parameter of type Thing and
returns as output how many copies of the input thing exist in the collection. Note that
things must be compares using the equals method.
Part C: Implement your Driver class
Implement a Driver class that works as follows:
• creates a collection class that can hold up to 10 things.
• uses the add methods to insert 5 items in the collection. You may use any arbitrary values in
in the objects to be inserted.
• The driver then calls the methods 3 through 9 in order. Note that you do not have to use a
Scanner to read any inputs from the user. On the other hand, use hard coded values for the
different methods’ inputs.
Grading
Your grade in this assignment is based on the following:
• Your submission meets specifications as described above.
• Add appropriate comments to your code.
• Variable names should convey meaning.
• At the top of each Java file, include your name, a brief description of the program and what it
does and the due date.
• All code blocks must be indented consistently and correctly. Blocks are delimited by opening
and closing curly braces. Opening and closing curly braces must be aligned consistently.
• You must use the exact same name (including upper case and lower-case letter) for all
methods as specified in the above description.
• The output of our program must be nicely formatted.
• You must follow the method requirements in terms of the number and data type of input
parameters and the output data type.
• The program is robust with no runtime errors or problems.
• The programs should display your name.
Part 2 Instructions
• Zip up Part1 and name it i.e. DillonArraysOfObjectCollectionPart1, but Do Not
submit it. Continue to Part2.
• Part2 is going to build on Part 1.
• After completion of Part2 and testing all your methods in the
ThingDriverCollection, follow the steps in Part2 to submit your project.
• Part1 and Part 2 will be in separate .zip folders, but the final submission will in
one project folder.
• If you have questions, please email me way before the deadline. Do Not email 1
or 2 fays before the due date. Email me in advance so I can have ample time to
respond.